Revision Part 1

Virulence factors are indeed molecules produced by bacteria that enhance their ability to colonize and cause disease in their host. Adhesins facilitate bacterial attachment to host cells or tissues, promoting colonization. Exotoxins are secretWhat are bacterial virulence factors, ed proteins that can damage host cells and how do they contribute to bacterial or alter host immune responses. Endopathogenesis? toxins are components of the bacterial cell wall, specifically lipopolysaccharides (LPS) in Gram-negative bacteria, which can induce inflammation and other host responses. These virulence factors collectively aid bacteria in infecting the host and causing disease Neurotoxins: Examples include botuCan you provide examples of exotoxins linum toxin produced by Clostridium produced by bacteria, and briefly explain botulinum, which blocks neurotransmittheir mechanisms of action? Neurotoxins ter release at neuromuscular junctions, leading to muscle paralysis. Enterotoxins cause intestinal disturbance Enterotoxins: One example is cholera toxin produced by Vibrio cholerae, which causes severe diarrhea by stimulating excessive secretion of water and electrolytes in the intestines. Cytotoxins Cytotoxins: An example is alpha-toxin produced by Staphylococcus aureus, which forms pores in host cell membranes, leading to cell lysis and tissue damage. Superantigens cause an intense immune response due to release of cytokines and T cells from host cells Endotoxins are actually part of the outer membrane of Gram-negative bacteria and are released when the bacte1/7 ria die or undergo lysis, not necessarily when the cell lyses. The main compoWhat are endotoxins, and how do they nent of endotoxins is lipopolysaccharide differ from exotoxins in terms of their (LPS), which can trigger strong immune structure and release? responses in the host, leading to inflammation and other symptoms. Pathogenicity islands are indeed clusters of genes located on the bacterial chromosome or on plasmids that encode virulence factors and other traits associated with pathogenicity. These genes can What are pathogenicity islands, and how include those encoding adhesins, toxins, do they contribute to bacterial virulence? secretion systems, and other factors that enhance the ability of the bacterium to cause disease. Pathogenicity islands are often acquired through horizontal gene transfer and can significantly contribute to the virulence of bacteria. Antigenic variation refers to the ability of pathogens, including bacteria, to alter their surface antigens in order to evade recognition and elimination by the host What is antigenic variation, and how immune system. This process can occur does it contribute to bacterial evasion of through various mechanisms, including the host immune system? changes in gene expression, mutations, horizontal gene transfer, or phase variation. By changing their surface antigens, bacteria can effectively "hide" from the host immune response One classic example of antigenic variation in bacteria is seen in Neisseria gonorrhoeae, the bacterium that causes Can you provide an example of how bacgonorrhea. Neisseria gonorrhoeae can teria employ antigenic variation to evade alter the structure of its surface protein the host immune system, and briefly excalled the pilus, which is involved in adplain the mechanism involved? hesion to host cells. This process, known as pilin antigenic variation, involves the expression of different variants of the 2/7 pilin gene. By switching between different pilin variants, the bacterium can evade recognition and clearance by the host immune system, facilitating persistent infection. Phase variation is a process by which bacteria can reversibly switch between different phenotypic states, often involving changes in the expression of specific What is phase variation, and how does genes or gene products. This phenomeit contribute to bacterial adaptation and non allows bacteria to quickly adapt to survival in the host environment? changing environmental conditions, including the host environment, and can contribute to their survival and persistence during infection. What is the main function of the Type I secretion system in bacteria? The main function of the Type I secretion system in bacteria is to transport proteins directly from the bacterial cytoplasm across both the inner and outer membranes into the extracellular environment. Which bacterial secretion system forms a needle-like structure composed of a polymerized protein called "pilin"? The Type III secretion system forms a needle-like structure composed of a polymerized protein called "pilin." This needle-like structure is used to inject bacterial effector proteins directly into host cells during infection. The Type II secretion system does Which bacterial secretion system uti- not transport unfolded proteins across lizes a complex machinery called the the cytoplasmic membrane. Instead, it "sec translocon" to transport unfolded transports fully folded proteins from proteins across the cytoplasmic mem- the periplasmic space across the outer brane? membrane into the extracellular environment. Which bacterial secretion system is In the Type V secretion system, the proknown as the "autotransporter" system, tein being secreted contains its own sewhere the protein being secreted con- cretion signal and is translocated across 3/7 tains its own secretion signal and is the outer membrane in a single polypeptranslocated across the outer membrane tide chain. in a single polypeptide chain? Which bacterial secretion system is involved in the assembly of long, tubular structures called "pili" on the bacterial surface, and these pili can serve various functions including adherence to host cells, biofilm formation, and twitching motility? The Type IV secretion system is involved in the assembly of long, tubular structures called "pili" on the bacterial surface. These pili can serve various functions, including adherence to host cells, biofilm formation, and twitching motility. The Type VI secretion system is indeed a Which bacterial secretion system is a contact-dependent mechanism that mecontact-dependent mechanism that me- diates the transfer of proteins directly diates the transfer of proteins directly from the cytoplasm of one bacterial cell from the cytoplasm of one bacterial cell to another. It plays a crucial role in bacto another? terial competition, interbacterial interactions, and virulence. The main function of the Sec protein translocation pathway in bacteria is to transport proteins across the cytoplasmic membrane, from the cytoplasm to the periplasmic space. This pathway is involved in the translocation of proteins synthesized in the cytoplasm, assisting in their secretion or insertion into the cyWhat is the main function of the Sec protoplasmic membrane. tein translocation pathway in bacteria? The Sec pathway typically transports unfolded or partially folded proteins across the cytoplasmic membrane, where they can then be further processed or transported to their final destination, which may include secretion out of the cell or integration into the membrane. It then facilitates the targeting of these proteins to the cytoplasmic membrane, where they are integrated into the lipid bilayer. This pathway is crucial for ensuring 4/7 What is the main function of the SRP proper membrane protein biogenesis in (Signal Recognition Particle) pathway in bacteria. bacteria? The main function of the Tat (Twin-arginine translocation) pathway in bacteria is to transport fully folded proteins across the cytoplasmic membrane, typWhat is the main function of the Tat ically from the cytoplasm to the periplas(Twin-arginine translocation) pathway in mic space. bacteria? Unlike the Sec pathway, which transports unfolded or partially folded proteins, the Tat pathway is specialized for the transport of fully folded proteins. what do the secretions systems allow the allow for virulence factors, biofilm formabacteria to do? tion, and bacteria communication Pili, also known as fimbriae, are hair-like appendages on the surface of many bacteria that play a crucial role in adherence What is a common mechanism used by to host cells during the initial stages of pathogenic bacteria to adhere to host infection. These structures allow bacteria cells during the initial stages of infection? to attach to specific receptors on the surface of host cells, facilitating colonization and the establishment of infection. The next step for many pathogenic bacteria after attachment to host cells is often the secretion of virulence factors or the induction of host cell signaling Once attached to host cells, what is the pathways to facilitate invasion. This can next step for many pathogenic bacteria involve mechanisms such as secretion to invade host tissues? systems to deliver toxins or effector proteins into host cells, induction of cytoskeletal rearrangements to promote bacterial uptake, or exploitation of host cell endocytic pathways. Which term refers to the process by which pathogenic bacteria are engulfed phagocytosis 5/7 by host cells into membrane-bound vesicles called phagosomes? After phagocytosis, some bacteria can This process is called "phagosome-lysoevade host immune responses by presome fusion inhibition" or simply "phagoventing the fusion of phagosomes with somal evasion." lysosomes. What is this process called? The term for the process by which some pathogenic bacteria induce localized changes in the host cell cytoskeleton to facilitate their internalization into host cells is "cytoskeletal rearrangeWhat is the term for the process by which ments" or "cytoskeletal manipulation." some pathogenic bacteria induce localized changes in the host cell cytoskeleDuring this process, pathogenic bacteria ton to facilitate their internalization into often exploit host cell signaling pathways host cells? to induce the rearrangement of actin filaments and other cytoskeletal components, leading to the formation of membrane protrusions such as filopodia or lamellipodia These enzymes are called "matrix metSome pathogenic bacteria produce en- alloproteinases" (MMPs) or "collagenaszymes that degrade components of the es." They target proteins such as collaextracellular matrix, allowing them to gen, elastin, and other components of spread through host tissues. What is the the extracellular matrix, breaking them term for these enzymes? down and facilitating bacterial spread through host tissues. The term for the strategy where pathogenic bacteria possess surface structures that mimic host cell molecules, alSome pathogenic bacteria possess sur- lowing them to evade host immune reface structures that mimic host cell mol- sponses, is "molecular mimicry." ecules, allowing them to evade host immune responses. What is the term for Molecular mimicry involves pathogens this strategy? expressing surface molecules that resemble host cell molecules, thus tricking the host immune system into tolerating or not recognizing the pathogen as foreign. 6/7 Some pathogenic bacteria produce biofilms, which are communities of bacteria embedded in a self-produced matrix. What is the term for the ability of bacteria within biofilms to resist the effects of antibiotics and host immune responses? The term for the ability of bacteria within biofilms to resist the effects of antibiotics and host immune responses is "biofilm-associated antimicrobial resistance" or "biofilm-mediated antimicrobial resistance." What is quorum sensing? the ability of bacteria in a biofilm to communicate with each other and coordinate their activities The term for the directed movement of bacteria towards or away from specific stimuli in their environment using flagella is "chemotaxis." Some pathogenic bacteria use flagella Chemotaxis allows bacteria to sense and for motility, allowing them to move torespond to chemical gradients in their wards or away from specific stimuli in environment, enabling them to move their environment. What is the term for towards attractants (positive chemothis directed movement? taxis) or away from repellents (negative chemotaxis). This mechanism helps bacteria to locate favorable environments for growth and survival or to avoid harmful substances. 7/7